Cylinder head



June 23, 1959 is. E. FRANKE 2,891,523

June 23, 1959 FRANKE 2,891,523

' CYLINDER HEAD Filed March 4 625-40,! E man 'c United Stes atet CYLINDER HEAD Gerhard E. Franke, Koln-Dellbruck, Germany, assignor to Kliickner-Humboldt-Deutz Aktiengesellschaft, Koln, Germany The present invention relates to a cylinder head for a valve-controlled four-stroke cycle fuel injection engine with which at approximately the end of the compression stroke, nearly the entire compressed air enters a precombustion chamber into which also the fuel is injected. Such pre-combustion chamber may be provided in the cylinder head or in the piston and communicates with the cylinder through a separate passage.

With valve-controlled four-stroke cycle internal combustion engines, that side of the bottom of the cylinder head which faces the cylinder is at the end of the compression stroke or at the beginningof the working stroke greatly heated by the hot combustion gases which leave the pre-combustion chamber and pass into the cylinder while expanding therein. While the heat adjacent the circumference of the cylinder head, i.e. where the cylinder head normally has no or few cavities can relatively quickly pass to the cooling zones, considerable heat accumulation is encountered by the so-called web, i.e. the narrowest separating wall portion between the openings for the inlet and the outlet valves.

It is, therefore, an object of the present invention to improve cylinder heads of the above mentioned type to such an extent that the thermal stresses to which the above mentioned web are normally subjected will be considerably reduced.

It is another object of this invention to provide an improved cylinder head of the type set forth in the preceding paragraph which is relatively simple and in which the reduction in the thermal stresses normally acting upon the web will be effected in a very simple manner.

These and other objects and advantages of the invention will appear more clearly from the following specification in connection with the accompanying drawings, in which:

Fig. 1 is a section through a portion of a cylinder and a cylinder head according to the present invention and pertaining to a four-stroke cycle fuel injection engine.

Fig. 2 is a bottom view of the cylinder portion shown in Fig. 1.

Fig. 3 is a section along the line III-III of Fig. 2.

Fig. 3a is a section somewhat similar to Fig. 3 in which the recess or communication channel between the valve inlets and outlets at the cylinder bottom is provided with sharp edges.

Fig. 4 is a section through a cylinder head somewhat similar to Fig. 3 but with the pre-combustion chamber in the piston.

The primary object of the present invention to provide a cylinder head in which too high thermal stresses of the web are to be avoided has been materialized ac cording to the present invention by providing that side of the cylinder head which faces the cylinder with a recess or passage representing a communication channel as short as possible between the openings for the inlet and outlet valves. This passage or channel considerably reduces the speed of the hot combustion gases Within the range of the web so that the said web will be heated to a less degree than those portions of the cylinder head which are approached to a greater extent by the piston end of the compression stroke approximately the entire compressed air is received by a pre-combustion chamber 8 which communicates with the main combustion chamber 9 of the cylinder 1 through a passage 7. The fuel is injected into the pie-combustion chamber 8. The hot gases which during operation of the engine and at the end of the compression stroke or at the start of the working stroke pass from the pie-combustion chamber 8 into the main combustion chamber 9, heat up the top of the piston (not shown) as well as the bottom of the cylinder head. In order to protect the cylinder head within the range of the smallestportion' between the openings for the inlet and outlet valves, i.e. in order to protect the so-called web 5 from being subjected to too high thermal stresses, the bottom of the cylinder .head is provided'with arecess or passage 6 forming the shortest communication between the. openings pertaining to the inlet and outlet valves respectively. This communication channel or passage 6 brings about that within the range of the web 5 the speed of the hot combustion gases leaving the passage 7 and expanding into the main combustion chamber 9 is considerably reduced so that the said web 5 is heated up to a less degree than those portions of the bottom of the cylinder head which are approached by the piston when the latter passes through its dead center position.

In conformity with a further development of the invention, the edges of the said communication channel or passage may be strongly rounded or may extend in an inclined manner relative to the bottom of said channel or passage as shown at 6a in Fig. 3.

However, the said edges may also be sharp-edged as shown at 6b in Fig. 3a in which instance they will bring about a whirling of the gases whereby the gases are greatly loosened up or opened up. The respective design of the said edges is expediently selected in each instance in conformity with other features of the engine. The pre-combustion chamber may also be in the piston 10.

The arrangement according to the present invention is particularly suitable for supercharged internal combustion engines inasmuch as the said recess or communication channel below the web 5 creates favorable conditions for the scavenging customary with supercharged engines.

It is, of course, to be understood that the present invention is, by no means, limited to the particular construction shown in the drawings but also comprises any modifications within the scope of the appended claims.

What I claim is:

1. In a cylinder piston arrangement for a four-stroke cycle fuel injection engine having a first engine element composed of a cylinder head provided with a bottom surface forming part of a main combustion chamber, a second engine element formed by a piston having a top surface forming another part of said main combustion chamber: a pre-combustion chamber provided in one of said engine elements and spaced from but in communication with said main combustion chamber, the bottom surface of said cylinder head also being provided with a pair of spaced recesses comprising valve surfaces for cooperation with an inlet valve and an outlet valve respectively, and a substantially straight groove providedin the bottom surface of-said cylinder head between said recesses and forming the shortest channel of communication therebetween.

'2. In a cylinder head for a four-stroke cycle fuel injection engine having a bottom surface forming part of a main combustion chamber: a pro-combustion chamber provided in said cylinder head and spaced from said bottom surface, channel means effecting communication between that part of the main combustion chamber which is formed by said bottom surface and said precombustion chamber, said bottom surface also being provided with a pair of spaced recesses comprising valve surfaces for cooperation with an inlet valve and an outlet valve respectively, and'a substantially straight groove provided intheobottom surface'ofsaid cylinder head between said recesses and forming: the shortest channel of communications therebetween.

3. Ina four-stroke'cycle fuel injection engine: a cylinder head with the bottom surface thereof forming part of a main combustion chamber and having a cylinder with a piston reciprocably mounted therein, a portion of said piston forming another part of said main combustion chamber and another portion of said piston forming a pre-combustion chamber, said pre-combustion chamber being arranged for direct communication with said main combustion chamber, said bottom surface also being provided with a pair of spaced recesses comprising valve surfaces for cooperation with an inlet valve and an outlet valve-respectively, and a substantially straight groove provided in the bottom surface of said cylinder head 4 between said recesses and forming the shortest channel of communication therebetween.

4. A cylinder piston arrangement according to claim 1, in which said spaced recesses are of substantially circular contour, and in which the substantially straight groove forming the shortest channel of communication between said recesses has its longitudinal edges substantially tangential to said spaced recesses.

5. A cylinder piston arrangement according to claim 1, in which the edges of said substantially straight groove are greatly rounded.

6. A cylinder piston arrangement according to claim 1, in which said substantially straight groove forming the shortest channel of communication between .said spaced recesses has a trapezoidal cross section in the direction transverse to the longitudinal extension of said groove, the shorter one of the two parallel sides of said trapezoidal cross section forming part of the bottom. of said groove and being equal in length tothe width of the bottom ofsaid groove.

7. A cylinder piston arrangement according'to claim 1, in which the edge portions of said substantiallystraight groove are sharp-edged.

References Cited in the file of this patent UNITED STATES PATENTS 2,658,493 Kloss Nov. 10, 1953 FOREIGN PATENTS 134,542 Austria ,Aug.'25, 1933 

